Smokeless tobacco analysis: Simultaneous extraction and purification of alkaloids, volatile N-nitrosamines, and polycyclic hydrocarbons for GC-MS/MS

Several smokeless tobacco products are available in the market and comprise complex chemical matrices. Sample preparation for analysis of the multiple classes of harmful compounds in smokeless tobacco products is highly cumbersome. In this study, a simultaneous extraction scheme was developed for three toxic analyte classes in smokeless tobacco products using a two-phase solution consisting of 5% aqueous NaOH and dichloromethane in a 1:4 ratio. The dichloromethane extract was used to analyze four alkaloids directly at levels greater than parts per million; however, passing the layer through a silica cartridge for further purification and concentration was necessary for determining 18 polycyclic aromatic hydrocarbons and four volatile N-nitrosoamines at the ppt level. The multitargets were determined by using gas chromatography with tandem mass spectrometry. The limits of detection for the 18 polycyclic aromatic hydrocarbons, four volatile N-nitrosoamines, three minor alkaloids, and nicotine were 0.2-1.2, 0.2-0.4, 0.6-1.0, and 10.2 mu g/g, respectively. Four different smokeless tobacco substrates were fortified with three levels of mixed standards, and the recoveries ranged between 83 and 110%. The method was highly efficient, reduced the sample amounts, solvents, and the time required by approximately 60%. The method was used to assay 18 smokeless tobacco products, and showed potentials in assaying drugs and other plant-based substrates.